Rejects network with gateway outside subnet

[waldiTM]

Creating an IPv6 subnet using podman fails if the gateway is not inside the subnet itself. In IPv6 this is a rather common setup, where the gateway uses the link-local range fe80::/10.

With IPv6 in Linux, using such a link-local address will just work with a normal routing setup. With IPv4 in Linux this will in theory also work, by using the special "onlink" flag.

Error: gateway fe80::1 not in subnet 2001::db8::/48